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Discussion Starter #1
Hi,

I just got a 68 V8 302 a month ago. About 2 weeks ago the car overheated and I replaced the thermostat and it fixed the problem. Yesterday it started to overheat again. What do you think that cause the problem? What’s the next component should I check?

Thanks
 

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Deposits and corrosion in the radiator reduce its efficiency over time. When was the last time you flushed it? Peak makes a good flush chemical, basically a weak acid, that helps to reduce these deposits. The way it works is you:

1. Drain all the fluid out and replace it with water plus the chemical. Then drive the car for 6 to 8 hours. But don't keep the stuff in there more than a week.
2. Drain, fill with clean water, run the engine until the thermostat opens and then for a few minutes longer, let cool then drain.
3. Repeat step 2 until you get clear water coming out.
4. Look inside the radiator and see if it made a difference. If not do it again but with a more concentrated mix of the weak acid.

When you're done refill with a 50-50 mix of antifreeze. I've heard guys trying a more concentrated mix, or even pure anti-freeze, but that's a bad idea since water transfers heat more efficiently that anti-freeze.

Also dispose of the antifreeze properly as well as the rinse chemicals. In my county that means dropping off the antifreeze at the local haz-waste drop off and flushing the rinse water down the toilet.
 

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I know the search engine on these forums lacks (tremendoulsy), but if you were to search "overheating", you'll find that a radiator replacement as happily solved the problem. Most of the time, like Yadmin says, the radiator is just old and full of crud. I have never witnessed a rad flush solving the problem, anything is possible and my experience is not real vast, but I bet the flushes are more preventative maintenance than anything. Make sure you have the correct size rad too, you never know what the PO's have done.

Other possible additives to over heating...

1.) Timing.
2.) Brakes draging.
3.) Alternator Binding.
4.) Worn Clutch Fan.
5.) Carb Air/Fuel Mixture.

I'm betting on cruddy old radiator.
 

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Discussion Starter #4
I'm leaning toward the radiator too. What's the recommended replacement fro the radiator ?

Thanks
 

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Check to see if the lower hose collapses when you rev the engine... It is common when the lower hose is replaced that the spring in it is lost. If it does collapse then you can make a spring for it or get a new hose with a spring in it. That could be your only problem.
 

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Hello elkgrove65,
You have gotten some GREAT advice.

I like o start with the simple thngs.
Never assume something is bad and just replace it.

PaulS makes a great point - -I would like to
add soemthing as well.

Start with the simple things - -have you checked and adjusted the belt tension?

I have had good luck periodically cleaning out the system with
"prestone flush" Follow directions.

An OLD trick - -start the motor and allow it to reach temp - -then on the
NONE fan side - - the side facing the front of the motor - - feel the radiator - -
it should be pretty uniform in temp (No cold spots).

BE CAREFUL - -watch the fan - -check on NON FAN side ONLY.

I would try a flush as described by Yadkin. PLease dispose of fluids properly
for our children and grandchildren. Watch out for puddles if you drain the cooling
system - -can be fatal to animals.

Try the little stuff first

Print DAD
 

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I know the lower rad hose spring thing can be a controversial topic, but I beleive that the springs are put in from the factory for when the radiator does clog up, it buys you some time until the radiator can be fixed. It may actually buy a few years because the clogging process is a slow one. SO, How sure am I of this?, not too sure, I still install them in my cars. Just in case, and Paul is right if your spring is missing - installing one could get you by for quite some time. If the hose is colapsing, it's a sure sign that the water pump is sucking coolant much faster/harder than the radiator will allow.
 

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Discussion Starter #8
Here are step that I will do based on all your advise:
1. Check to make sure that the lower hose not collapsing.
2. Flush the radiator with "prestone flush".

Will report back the result.
Thanks
 

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Discussion Starter #10
I just checked the lower hose and it is OK when I rev the engine. I also emptied the radiator and the fluid looks clean. How do I chech to see if the thermostat and the water pump are working?
 

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Did it actually overheat or did your temp gauge just show hot? Cause it might just be a bad temp gauge as well.

Glad to see another Elk Grove Mustang member!
 

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Try putting a new radiator cap on it. If the cap is old and doesn't seal or its spring pressure is weak it will not hold the proper pressure and it will overheat. Cheap part to replace or if you know someone with a pressure tester they can verify if yours is OK.
 

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I just checked the lower hose and it is OK when I rev the engine. I also emptied the radiator and the fluid looks clean. How do I chech to see if the thermostat and the water pump are working?
With the engine cold, start it up and monitor the temperature of the radiator by touching the grill side with your hand. It should be cold until the thermostat opens, then get hot quickly after it opens.

If the water pump wasn't working then the radiator would never get hot and the engine would overheat quickly.

Good advice by rickster65 on the new cap.
 

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Discussion Starter #16
Bold, the temp gauge showed Hot on Sunday.

And here what I did yesterday. I drained out the radiator to check the fluid and i looked clean. Fill the rad up again with 50/50 (coolanr/water). Make sure the cap is tight (16 lbs cap). Cold start the stang and let it idle for 15 minutes in 97 degrees weather with no shade over the car. After few minutes I can feel to rushing in the top hose and the hose getting warm real fast. Maybe that indicates the thermostat is working. After 15 minutes the stock temp gauge needle is right in the middle. I did not drive it because the brake power booster is shot. So do you guys think my car is OK now?
 

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I would get an upgraded radiator anyway. Since older mustangs are known to overheat, a aluminum 3 or 4 row is a great upgrade and the engine runs much cooler. Removing the stock fan and installing an electric fan is a great addition too. The least you can do is fix the booster and drive it with a load and see if it is ok. If not, maybe time to upgrade.
 

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Dont make the same mistakes i did and start replacing everything without finding the problem first. :nogrinner
 

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You can check the thermostat by putting it in a pot of water and checking to see if it opens at a pre-determined temperature. A bad w/p will make noise I am pretty sure. I had to replace my entire cooling system last year after some bad overheating. New 3 core radiator, fan shroud, 5 blade fan fixed it
 
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